Method for concentrating aluminum silicates and zircon from beach sand



United States Patent Ofifice 3,097,162 Patented July 9, 1963 snazrsz METHOD FOR CONCEN'IRATING ALUMINUM SILICATES AND ZRCON FROM BEACH SAND Robert E. Baarson, La Grange, and Charles W. Jonaitis,

Chicago, 'Ill., assignors to Armour and Company, Chicago, 111., a corporation of Delaware No Drawing. Filed Dec. 2, 1960, Ser. No. 73,231 2 Claims. (Cl. 209-466) quartz, while containing a small proportion of valuable minerals, among them being titanium oxide minerals like i'lmenite and rutile, in addition to the heavy minerals 'such as kyanite-'sillimanite, zircon, s'tauro'lite and dumo-r- -tierite. Usually the content of quartz in these sands will be at least 90, while the content of the various heavy minerals may range irom a trace to upwards of 4%.

The most valuable .product at present in beach sands is the titanium oxide minerals. These-and other conductive and magnet-responsive heavy minerals are recovered from beach sand deposits by complicated and expensive procedures. For example, the steps in one of these processes involves passing the beach sands through a series of spiral concentrators to make a rough separation of the titanium oxide and other heavy minerals from the quartz. F ollowing the rough separation, there are cleaner and recleaner spiral circuits to upgrade the concentrate, and a large amount of the middling material is recycled through these circuits to increase recovery. The titanium minerals in the heavy mineral concentrate are then further separated and concentrated by electrostatic and magnetic separators. The electrostatic separation removes the ilmenite and rutil-e while induced roll magnets are employed to remove the staurolite and dumortierite.

The resultant nonconductive, non-magnetic reject fractions from this operation contain minerals which are in themselves valuable. The composition of these tractions is roughly 40 to 50% aluminum silicates, also referred to as the kyanite-sillimanite fraction, 20% to 30% zircon, and 25 to 40% quartz. Heretofore, there has been no practical and commercially feasible way of recovering these valuable-minerals from the reject beach sand concentrates. It is with these fractions that the present invention is principally concerned.

The problem involved in using such non-conductive non-magnetic ores to obtain an aluminum silicates and zircon product of high grade in economically practical recoveries has heretofore received little attention. The industry has: always realized that this discarded material contains valuable heavy minerals but no commercially feasible method has up to now been devised to obtain the minerals in proper grade and recovery. Applicants have solved the problem and have provided through this invention a flotation method which enables the bulk concentration of the valuable aluminum silicate and zircon frac-..

tions from the non-conductive, non-magnetic fraction of beach sand concentrates.

It is therefore a general object of this invention to provide a method for concentrating the aluminum silicates and zircon minerals in beach sands, and specifically, to provide a flotation method for accomplishing the concentration of aluminum silicates and zircon from beach sand concentrates from which the titanium oxide minerals have for carrying out the bulk separation of aluminum silicates in reject sands concentrates from the quartz and zircon therein, and further, to provide a method for separating the zircon from the quartz without the need for additional quantities of collecting agent. Further objects and advantages will appear as the specification proceeds.

In practicing the present invention, the beach sand fraction from which the titanium oxide minerals have been separated is formed into a floatation feed. The particles of this fraction, as received, range from about 30 to +200 mesh. To the flotation feed is added an amine collector, and a depressant selected from the group consisting of dextrins, gums and starches. The aqueous feed is adjusted to an alkaline pH, and a frother, such as pine oil or cresylic acid, is introduced into the feed. Amine collectors impart some frothing in themselves and for this reason the use of a frothing agent in the process is optional and may be omitted. Employing standard fiotation procedures, an aluminum silicates concentrate is obtained in the underflow while a combined zircon and quartz product is recovered in the overflow.

The overflow'product may then be re-pulped and worked into a flotation feed to which is added a depressant in the form of a fluorine containing acid. The pH of this feed is adjusted to below about 6.0, preferably about 3.0. A frother, as in the initial flotation operation, may be added. It is generally unnecessary to introduce further quantities of the amine collector. Again employing conventional flotation techniques, a zircon concentrate is obtained in the overflow leaving a tailing consisting primarily of quartz.

Any amine collector can be employed. Preferably, however, the amine floatation agent is a primary amine containing a hydrophobic group of from 6 to 22 carbon atoms. Mixed amines like primary, tallow and soya amines are suitable. Both mono and polyamines may be used. Very satisfactory results are obtained when the amine flotation agent is used in the form of a water-soluble salt thereof, such as an amine acetate or hydrochloride salt. Amine-nitrile blends sold under the trademark Armoflote, and amines alone, taken up in a frother such as pine oil or an alcohol such as isopropanol, are also effective.

To achieve theoutstanding results of the present invention it is only necessary to add small quantities of the collecting agent to the ore. Usually, from about 0.1 to about 4.0 pounds of the agent per ton of ore will be satisfactory, with from 0.3 to about 1.0 pound per ton being preferred.

The pH of the aqueous feed formed from the starting beach sand fraction may be controlled by the addition of minor amounts of such inorganic alkaline reagents as sodium or potassium hydroxide. A pH of from 7.5 to 12 may be used but a range of 8 to 10 is preferred. The important point is to have a suflicient amount of the alkaline reagent present to maintain the pH of the alkaline side.

The depressant employed in bringing about a separation of the aluminum silicates from the zircon and quartz may, as indicated, be selected from the group consisting of dextrins, gums and starches. These agents have the effect of depressing the aluminum silicate fraction of the beach sand permitting the zircon and quartz flotation to be recovered in the overflow.

The fluorine containing acid employed to effect a separation between the zircon and quartz is preferably hydrofluoric acid, although other fluorine containing acids 3 4 can be substituted as well as mixtures of hydrofluoric Metallurgical Results acid and other fluorine containing acids.

The pulp density in the conditioning and flotation cirweight, weight, Percent percent percent cuits may be varied widely. In the conditioning circuit Product grams 136mmt h grade recovery the solids may be as low as 25%. However, 60 to 85% 5 mmem s solids is preferred and 70% solids is considered an opti- A1 s'li ate mum condition. In the flotation circuit the solids may ummum l c t 1 32 it? 3538 52% it? run as high as 40% and as low as 15 0. A 25% pup density, however, is especially eflective for flotation. Quartz con "i 146 29 2 '87 'Ihe flotation operations described above can be carried 10 COmPOSlte out in the usual type of flotation cells provided with means for supplying an to the lower portion of the cells. It 1s EXAMPLE H significant that the method of this invention permits a clean separation to be made between all of the aluminum Preparation of ore As received.

silicates from the zircon and quartz on the one hand Flotation machine Fagergren. and the zircon from the quartz on the other. The sepa- Water Dlstilled. rate mineral concentrates can be further upgraded by Temperature C.

Reagents and Conditions Conditions Reagents, pounds per ton Point of addition Time Float Percent pH Starch Armac NaOH Pine HF cond. (min) solids 3366 T oil (48%) 9.1 T 0.8 rougher 7.3 3.0 0.12 0 0.17 2nd mugh 213 F 0.2 0.17 Zircon cone 1 (L08 NOTE.-1st and 2nd ronghers filtered and combined in cell for addition of hydrofluoric acid (48%) and subsequent flotation. Starch 3366 obtained from Corn Products. (Unmodified Corn Starch.) V

gravity separation, electrostatic or magnetic separation, Metallurgical Results etc. to give the very high grade required of these minerals. 0 This procedure enables the recovery of 90% or more of W We t the aluminum silicates and zircon contained 1n the beach Product f i i Eggs; gggg 5,3253%, sand concentrates. minerals Whereas these materials were treated as a waste product in normal beach sand operations from which titanium g silicates oxide minerals were concentrated the method of this illz r c0110 iii; iiig gii i 2%.?) 23:2 vention now provides a practical and commercially feasible Quartz C0110 5 means for recovering valuable products from these waste Composite 499 materials.

This invention is further described in the following specific examples.

EXAMPLE I EXAMPLE III Preparation of ore As received. Preparation of ore As received. Flotation machine Fagergren. Flotation machine Fagergren. Water Distilled. Water Distilled. Temperature 25 C. Temperature 25 C.

Reagents and Conditions Conditions Reagents, pounds per ton Point of addition Time Float Percent pH Dextrin Armae NaOH Pine HF i 00nd. (min) solids 164 T oil (48%) l 1 20 0t 8 Tougher i g 2 2.0 0 1 o. 17 1 v 0.04 2nd rousher 1 2% 0 2 0 17 Zircon cone "5 ""'i% 0 O8 l I-Initial; F-Final. N era-1st and 2nd roughers filtered and combined in cell for addition of hydrofluoric acid (48%) and sub-- sequent flotation. Dextrln 164 obtained from Corn Products. Armac T is an acetate salt of tallow amine.

Reagents and Conditions Conditions Reagents, pounds per ton Point of addition Time Float Percent pH Dcxtrin Armae Pine HF NaOH cond. (min) solids 164 T oil (48%) 7.8 I Trace mughe i 2% 35 a. 2.0 0. 2 0.17 q

.- race 2nd 2 e. 35 l. 0.2 0 17 Zircon conc E 0 08 97 No'rE.-1st and 2nd roughers filtered and combined in cell for addition of hydrofluoric acid (48%) and subsequent flotatlon. A minute amount of caustic was necessary to raise the pH of the roughers.

Metallurgical Results trate. Percent Heavy Mineral essentially is the total heavy mineral grade in each product obtained, with the Weight, Weight, Percent Percent Percent remainder being quartz. Percent Grade indicates the Pmduct grams Percent heavy gTade Temvery grade of the mineral being concentrated, taking into acminerals 20 count both the quartz and other heavy minerals as con- Alummum silicates taminants. Percent Recovery represents that portion of cone 153 so. 5 97. so 95. 0 63,7 the total mineral appearing in the particular product that gigg ggg fits 28-1 6% 0 5 is considered to be the cencentrate.

While in the foregoing specification this invention has compmte 501 been described in relation to a specific embodiment thereof and many details have been set forth for this embodi- EXAMPLE IV merit, it will be apparent to those skilled in the art that the preparation f ore As receivg invention is susceptible to other embodiments and that Fl t i hi Fagergren 30 many of the details set forth herein can be varied widely Water Distilled. Without departing from the basic concepts of the inven- Temperature 25 C. tion.

Reagents and Conditions Conditions Reagents, pounds per ton Point of addition Time Float Percent pH Dextrin Duo- NaOH Pine HF cond (min) solids 164 mac C 011 (48%) 0. 04 0.2 0.17 2 54 Zircon conc 0' 08 Norn-lst and 2nd roughers filtered and combined in cell for addition of hydrofluoric acid (48%) and subsequent flotation. Dextrin 164 obtained from Corn Products. Duomac O is a diacetate salt of a coco diamine.

Metallurgical Results Weight, Weight, Percent Percent Percent Product grams percent heavy grade recovery minerals Aluminum silicates cone 174 34. 96.23 95 69 0 Zircon cone. 192 38.3 91.34 60 S8 5 Quartz conc 135 26. 9 4. 91

Composite 501 REMARKS We claim:

1. In a process for the concentration of quartz, aluminum silicate and zircon from a non-conductive, nonmagnetic fraction of beach sand concentrate, comprising the steps of floating a zircon and quartz fraction from the aluminum silicates in the sand in an aqueous solution containing an amine collector and a depressant selected from the group consisting of dextrins, gums and starches, said aqueous solution being at a pH of from about 7.5 to about 12, and then floating the zircon from the quartz of said zircon-quartz fraction in the presence of a fluorinecontaining acid and at a pH from about 6.0 to about 2.0.

2. In a process for the concentration of quartz, aluminum silicate and zircon from a non-conductive, nonmagnetic fraction of beach sand concentrate, comprising the steps of floating a zircon and quantz, fraction from the aluminum silicates in the sand in an aqueous solution at a pH of about 8.0 containing an amine collector and a depressant selected from the group consisting of dextrins, gums and starches, said amine collector having at least one hydrophobic gnoup of from 6 to 22 carbon atoms, and then floating the zircon from the quartz of said zircon-quartz fraction, without adding more of the collecting agent in the presence of a fiuorinecontaining acid and at a pH of about 3.0.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS 2,177,985 Harris Oct. 31, 1939 2,205,503 Tmtter June 25, 1940 2,341,046 Kirby Oct. 9, 1940 8 Baaa'son May 21, 1957 Uhland Feb. 7, 1961 OTHER REFERENCES Gaudin: Flotation, page 500 (Sillimanite and Kyan'ite), Second Edition, McGraw-Hill, 1957. 

1. IN A PROCESS FOR THE CONCENTRATION OF QUARTZ, ALUMINUM SILICATE AND ZIRCON FROM A NON-CONDUCTIVE, NONMAGNETIC FRACTION OF BEACH SAND CONCENTRATE, COMPRISING THE STEPS OF FLOATING A ZIRCON AND QUARTZ FRACTION FROM THE ALUMINUM SILICATE IN THE SAND IN AN AQUEOUS SOLUTION CONTAINING AN AMINE COLLECTOR AND A DEPRESSANT SELECTED FROM THE GROUP CONSISTING OF DEXTRINS, GUMS AND STARCHES, SAID AQUEOUS SOLUTION BEING AT A PH OF FROM ABOUT 7.5 TO ABOUT 12, AND THEN FLOATING THE ZIRCON FROM THE QUARTZ OF SAID ZIRCON-QUARTZ FRACTION IN THE PRESENCE OF A FLUORINECONTAINING ACID AND AT A PH FROM ABOUT 6.0 TO ABOUT 2.0. 